The present invention relates to an intermediate transfer type thermal transfer recording method.
The intermediate transfer type thermal transfer recording method is a method wherein a melt-type thermal transfer recording medium is used to form first an image on an intermediate transfer medium according to image signals, and the image obtained on the intermediate transfer medium is then transferred onto an image receptor.
The intermediate transfer type thermal transfer recording method is an image formation method wherein an intermediate transfer printer such as shown in FIG. 1 or FIG. 2 is used. In FIGS. 1 and 2, numeral 10 denotes a rotatable intermediate transfer drum and numeral 20 denotes a rotatable intermediate transfer belt. Numeral 11 denotes a recording part which is arranged so. that a thermal transfer recording medium 12 can be pressed against the intermediate transfer drum 10 or intermediate transfer belt 20 with a heating head 13. In recording, the recording medium 12 is moved in the direction indicated by an arrow as the intermediate transfer drum 10 or intermediate transfer belt 20 rotates. Numeral 14 denotes a transfer part which is arranged so that an image receptor 15 can be pressed against the intermediate transfer drum 10 or intermediate transfer belt 20 with a pressing roller 16. In transferring, the image receptor 15 is moved in the direction indicated by an arrow.
The thermal transfer recording medium 12 is heated with the heating head 13 so as to selectively soften or melt portions of the colored ink thereof, which are transferred onto the surface of the intermediate transfer drum 10 or intermediate transfer belt 20 as an intermediate transfer medium. While the intermediate transfer drum 10 or intermediate transfer belt 20 and the recording medium 12 are thus moved in the directions indicated by the arrows, respectively, the colored ink is transferred onto the intermediate transfer drum 10 or intermediate transfer belt 20, thereby forming an ink image 17 thereon. As the intermediate transfer drum 10 or intermediate transfer belt 20 rotates, the ink image 17 is moved to the transfer part 14, pressed against the image receptor 15 there, and transferred onto the image receptor 15 to form a final ink image 18 thereon.
According to such an intermediate transfer type thermal transfer recording method, the ink of the recording medium which is heated with the heating head 13 is transferred onto a smooth surface of the intermediate transfer drum 10 or intermediate transfer belt 20. Hence, the problem involved in a common thermal transfer method of the type that unclear transferred images are likely to be formed on an image receptor paper of which the surface is poor in smoothness-is overcome. Further, according to the intermediate transfer type thermal transfer recording method, ink images 17 on the intermediate transfer drum 10 or intermediate transfer belt 20 are transferred onto the image receptor 15 by pressing thereagainst under a large pressure with the pressing roller 16. Hence, the quality of the thus obtained images is not subject so much to the superficial conditions of the image receptor.
In the aforesaid intermediate transfer type thermal transfer recording medium, the surface of the intermediate transfer drum 10 or intermediate transfer belt 20 is formed of a material of releasing properties such as silicone resin or rubber, fluorine-containing resin or rubber, or the like to facilitate release of the ink image 17 therefrom. Further, when the ink image 17 formed on the intermediate transfer drum 10 or intermediate transfer belt 20 is transferred onto the image receptor 15, it is necessary that the ink is in a softened or molten state. Therefore, a means is usually adopted wherein a heater is contained in the intermediate transfer drum 10 intermediate transfer belt 20, or the pressing roller 16 to heat the ink into a softened or molten state.
However, the aforesaid intermediate transfer type thermal transfer recording method involves two problems: (1) when the image receptor is a paper sheet, a lusterless image is obtained on the paper sheet and (2) when the image receptor is an OHP sheet (transparent sheet for an overhead projector), the image obtained on the OHP sheet is low in light transmittance and therefore the projection of the imprinted OHP sheet by means of an OHP provides a dull projected image.
In view of the problems of the foregoing prior art, it is an object of the present invention to provide an intermediate transfer type thermal transfer recording method which is capable of providing a lustrous image on a paper sheet as an image receptor and providing an image with high light transmittance on an OHP sheet as an image receptor, resulting in a clear or vivid projected image.
This and other objects of the present invention will become apparent from the description hereinafter.